The present invention relates generally to the extraction of juice from fruits, particularly citrus fruits such as oranges, lemons, grapefruit and the like.
It has been generally known heretofore from U.S. Pat. No. 2,767,644, granted to F. W. Bireley on Oct. 23, 1956, as well as from later improvements thereon, to provide citrus extraction apparatus wherein a pair of rotatable confronting parallel frusto-conical discs cooperate with stationary wall forming means therebetween in a manner to form separate pressure-applying paths which respectively converge from their inlet ends to their outlet ends in the direction of rotation of the discs. Whole fruits are introduced and gripped between resilient grooved surfaces of the discs that drive the fruit through a stationary or rotary knife that severs the fruit into half-sections, these half-sections then being moved into the respective pressure-applying paths and past slitting knives which nick the cut faces of the sections so that the sections can be progressively compressed between each disc and its associated stationary perforate wall.
The Bireley type citrus juice extractor has been found to be a durable high-production machine which is economically operable for long operating periods. A main problem, however, with the Bireley type extractor has been high peel oil in the juice, and a number of improvements have been made on it in an effort to produce a higher quality of juice with lower peel oil. For example, one such significant improvement is that which is disclosed in U.S. Pat. No. 3,351,000, granted to L. B. Alexander on Nov. 7, 1967, wherein a final open bar grid section is introduced into the stationary wall structure following the perforated portion thereof, so as to relieve pressure on the peel of the fruit section during its final high compression in the pressure-applying path. A rotatable roll is also mounted so as to extend transversely of the bars of this section, the roll having axially spaced circumferential rows of projections or teeth for engaging the bulging pulp between the bars in a manner to drive the compressed fruit sections against a knife blade positioned to sever the juice-bearing pulp from the peel of the section.
Due to the higher quality of juice with lower peel oil which could be obtained from the foregoing improvements, early consideration was given to the possibility of applying the features of the Alexander patent to the structure of the Bireley type extractor. It soon became evident, however, that the use of parallel confronting frusto-conical discs would not provide a sufficiently wide spacing to permit the installation of the two rotatable rolls as would be required to finally process the fruit sections of the separate pressure-applying paths. It also became evident that, if the spacing between the parallel frusto-conical discs was sufficiently increased so as to be able to accommodate the two rotatable rolls, the spacing of the discs would be so great at the inlets to the pressure-applying paths that the confronting discs could not be utilized to feed the whole fruits to the cutting means in the manner usually employed in the Bireley extractor.
According to the present invention, the problems as just described above have been solved in a unique and improved design in which the frusto-conical discs are disposed in rotatable tilted relation, rather than in the previously used parallel relation. The confronting discs are tilted in such a manner that a point of minimum spacing will occur adjacent the inlet to the pressure-applying paths, and a point of maximum spacing will occur adjacent the outlet of the pressure-applying paths, this latter spacing providing the required necessary space for the mounting of the two roll members. The feed problem is also solved in that whole fruit may be introduced in advance of such point of minimum spacing, and since the discs are approaching the point of minimum spacing, the introduced fruit will be firmly gripped, even though of varying size, and carried to the cutting means without injury or slipping which could produce undesirable peel oil. As thus arranged, the formerly used fruit-gripping grooves on the discs are no longer needed or necessary.
In the development of the present invention, consideration has also been given to the heretofore known rotary screening devices of the character disclosed in U.S. Pat. No. 2,149,017, granted to C. W. Gordon on Feb. 28, 1939; and the continuous rotary press arrangement as disclosed in U.S. Pat. No. 2,084,229, granted to D. H. J. Van Maanen on June 15, 1937. While these patents both disclose the concept of rotatably mounted confronting discs in tilted relation, it will be observed that the discs are in each case arranged with their maximum spacing at the point of supply of the material that is to be processed. Obviously, the disc orientation of these patents would not solve the problems which have been solved by the disc arrangement as utilized in the present invention.